Synthesis of derivatives of C-nucleoside analogues using 'push-pull' functionalized monosaccharides

7-Deoxy-1,2:3,4-di-O-isopropylidene-alpha -D-galacto-heptopyranos-6-ulose (I) reacted with carbon disulphide and methyl iodide in the presence of a base to furnish 7,8-dideoxy-1,2:3,4-di-O-isopropylidenegalacto -oct-7-enopyranos-6-ulose (2). This 'push-pull' activated unsaturated monosaccharide underwent a ring closure reaction with hydrazine hydrate to give the 'inversed' C-nucleoside analogue 3. Compound I and malononitrile yielded the 7-cyano-6,7-dideoxy- 1,2:3,4-di-O-isopropylidene-6-methyl-alpha -D -oct-6-enopyranurononitrile (4). Treatment of 4 with carbon disulphide and methyl iodide in the presence of a base afforded the sugar push-pull' butadiene 5 which was transformed into the pyridine nucleoside analogue 6. (C) 2001 Elsevier Science Ltd. All rights reserved.